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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of liability recognized arising from contingent consideration in a business combination.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Fair value of financial and nonfinancial obligations.

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Amount of noncurrent assets classified as other.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Assets
Investments	$ 10,176	$ 14,908
Investments	378
Derivative assets	387	130
Liabilities
Contingent consideration	852	935	$ 945	$ 891
Derivative liabilities	204	217
Commercial paper
Assets
Investments	30	159
Corporate notes and bonds
Assets
Investments	6,866	9,806
Asset-backed securities
Assets
Investments	$ 1,288	1,542
Liabilities
Primary weighted average life of collateral	5 years
U.S. government and agency securities
Assets
Investments	$ 1,431	2,042
Foreign government bonds
Assets
Investments	538	733
Mortgage-backed securities
Assets
Investments	23	626
Fair Value, Measurements, Recurring
Assets
Investments	10,065	14,531
Other assets	489	652
Derivative assets	387	130
Total assets	10,941	15,313
Liabilities
Contingent consideration	852	935
Derivative liabilities	204	217
Total liabilities	1,056	1,152
Fair Value, Measurements, Recurring \| Foreign exchange contracts
Assets
Derivative assets	233	48
Liabilities
Derivative liabilities	60	162
Fair Value, Measurements, Recurring \| Currency options
Assets
Derivative assets	154	80
Liabilities
Derivative liabilities	4	0
Fair Value, Measurements, Recurring \| Interest rate swap contracts
Assets
Derivative assets	0	2
Liabilities
Derivative liabilities	140	55
Fair Value, Measurements, Recurring \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	196	172
Other assets	236	171
Derivative assets	0	0
Total assets	432	343
Liabilities
Contingent consideration	0	0
Derivative liabilities	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring \| Quoted Prices In Active Markets for Identical Assets (Level 1) \| Foreign exchange contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring \| Quoted Prices In Active Markets for Identical Assets (Level 1) \| Currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring \| Quoted Prices In Active Markets for Identical Assets (Level 1) \| Interest rate swap contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Assets
Investments	9,869	14,359
Other assets	253	481
Derivative assets	387	130
Total assets	10,509	14,970
Liabilities
Contingent consideration	0	0
Derivative liabilities	204	217
Total liabilities	204	217
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Foreign exchange contracts
Assets
Derivative assets	233	48
Liabilities
Derivative liabilities	60	162
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Currency options
Assets
Derivative assets	154	80
Liabilities
Derivative liabilities	4	0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Interest rate swap contracts
Assets
Derivative assets	0	2
Liabilities
Derivative liabilities	140	55
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Assets
Investments	0	0
Other assets	0	0
Derivative assets	0	0
Total assets	0	0
Liabilities
Contingent consideration	852	935
Derivative liabilities	0	0
Total liabilities	852	935
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Foreign exchange contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Interest rate swap contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring \| Commercial paper
Assets
Investments	30	159
Fair Value, Measurements, Recurring \| Commercial paper \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	0	0
Fair Value, Measurements, Recurring \| Commercial paper \| Significant Other Observable Inputs (Level 2)
Assets
Investments	30	159
Fair Value, Measurements, Recurring \| Commercial paper \| Significant Unobservable Inputs (Level 3)
Assets
Investments	0	0
Fair Value, Measurements, Recurring \| Corporate notes and bonds
Assets
Investments	6,765	9,678
Other assets	101	128
Fair Value, Measurements, Recurring \| Corporate notes and bonds \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| Corporate notes and bonds \| Significant Other Observable Inputs (Level 2)
Assets
Investments	6,765	9,678
Other assets	101	128
Fair Value, Measurements, Recurring \| Corporate notes and bonds \| Significant Unobservable Inputs (Level 3)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| Asset-backed securities
Assets
Investments	1,271	1,476
Other assets	17	66
Fair Value, Measurements, Recurring \| Asset-backed securities \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| Asset-backed securities \| Significant Other Observable Inputs (Level 2)
Assets
Investments	1,271	1,476
Other assets	17	66
Fair Value, Measurements, Recurring \| Asset-backed securities \| Significant Unobservable Inputs (Level 3)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| U.S. government and agency securities
Assets
Investments	1,265	1,835
Other assets	166	207
Fair Value, Measurements, Recurring \| U.S. government and agency securities \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	0	68
Other assets	54	0
Fair Value, Measurements, Recurring \| U.S. government and agency securities \| Significant Other Observable Inputs (Level 2)
Assets
Investments	1,265	1,767
Other assets	112	207
Fair Value, Measurements, Recurring \| U.S. government and agency securities \| Significant Unobservable Inputs (Level 3)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| Foreign government bonds
Assets
Investments	538	732
Other assets	0	1
Fair Value, Measurements, Recurring \| Foreign government bonds \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| Foreign government bonds \| Significant Other Observable Inputs (Level 2)
Assets
Investments	538	732
Other assets	0	1
Fair Value, Measurements, Recurring \| Foreign government bonds \| Significant Unobservable Inputs (Level 3)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| Mortgage-backed securities
Assets
Investments	0	547
Other assets	23	79
Fair Value, Measurements, Recurring \| Mortgage-backed securities \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| Mortgage-backed securities \| Significant Other Observable Inputs (Level 2)
Assets
Investments	0	547
Other assets	23	79
Fair Value, Measurements, Recurring \| Mortgage-backed securities \| Significant Unobservable Inputs (Level 3)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| Publicly traded equity securities
Assets
Investments	196	104
Other assets	182	171
Fair Value, Measurements, Recurring \| Publicly traded equity securities \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	196	104
Other assets	182	171
Fair Value, Measurements, Recurring \| Publicly traded equity securities \| Significant Other Observable Inputs (Level 2)
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring \| Publicly traded equity securities \| Significant Unobservable Inputs (Level 3)
Assets
Investments	0	0
Other assets	$ 0	$ 0